Lens-Free Triple Quadrupole MS and Ion Transfer Efficiency at Interfaces for Environmental Monitoring
News Mar 19, 2012
Analytical labs deal with literally thousands of environmental samples often in dirty or complicated matrices and they require a reliable work-horse technology that can give precise and intuitive data without the need for complex sample preparation. Triple quadrupole mass spectrometry (TQ MS) coupled with gas chromatography (GC) has become the reliable industry standard.
Fundamental to MS is the creation, transfer, containment and detection of product and daughter ions. Improving efficiency at any of these stages predisposes an overall performance improvement in robustness and sensitivity, which analytical laboratories would welcome. Within the widely accepted technique of triple quadrupole MS (TQ MS), the efficiency of ion transfer between the quadrupole mass analyzers and the Q2 collision cell in a TQ MS is critical for instrument robustness and sensitivity - qualities that have made triple quads indispensable in modern quantitative MS.
• Gas collisions can increase the efficiency of a lens-free, RF-only interface between a quadrupole and collision cell, but significantly reduce the efficiency of lens-based interfaces.
• Collision pressure, energy and mass have little influence on the ion transfer efficiency of a lens-free interface, while they significantly change the efficiency of lens-based interfaces.
• Overall, a lens-free, RF-only interface is simpler to tune and maintain and more robust than a lens-based interface.
• The lens-free approach also provides increased mass stability resulting in significantly higher efficiency.